Battery electric vehicles, extended range electric vehicles, and strong hybrid electric vehicles are propelled using motor torque from one or more electric traction motors. The motors may draw electrical energy from or deliver a charge to the various battery cells of a rechargeable battery pack depending on the vehicle operating mode. The battery pack may include multiple rows of battery cells that collectively generate a substantial amount of heat during vehicle operation. As a result, thermal management systems are used to help regulate the temperature of the battery pack.
Thermal management systems are typically configured with a fluid pump and a supply of liquid coolant. The fluid pump circulates the coolant through a closed loop of conduit to cool the battery cells and associated power electronics. One or more heat exchangers, condensers, evaporators, and other fluid handling components extract the heat from the coolant after the coolant exits the battery pack. Direct refrigerant cooling systems are used in some emerging vehicle designs as an alternative technique for battery cooling. Direct refrigerant cooling systems, which forego some of the complexity of conventional coolant loops, use a supply of refrigerant to conductively cool the various battery cells.